TWI462158B - Film forming composition - Google Patents

Description

Membrane forming composition

The present invention relates to a film forming composition for diffusing impurities when manufacturing an impurity semiconductor.

The manufacturing technology of semiconductors is an indispensable technology in the manufacture of electronic products such as integrated circuits, and it is the main task in the electronics industry today. In the semiconductor manufacturing process, an impurity is mixed (doped) into an intrinsic semiconductor such as germanium or germanium to produce an impurity semiconductor such as a P-type semiconductor having a hole and an N-type semiconductor having free electrons. These impurity semiconductors, although currents are usually unable to pass, are small in energy required to jump from the valence band to the conduction band, and can be easily converted to allow current to pass as long as a certain voltage is applied.

The impurity element doped into the germanium substrate, the P-type semiconductor uses a group 13 element such as boron or gallium, and the N-type semiconductor uses a group 15 element such as phosphorus, arsenic or antimony. Various methods of diffusion of impurities have been developed, such as gas diffusion methods, solid diffusion methods, and coating diffusion methods, which are widely known.

For example, Patent Document 1 describes a method of diffusing impurities by a solid diffusion method and a dopant film produced by the method.

On the other hand, the coating diffusion method is a method of using a coating liquid containing an impurity, by applying it onto a semiconductor substrate, and then volatilizing the solvent to form an impurity diffusion source layer, which is then subjected to thermal diffusion treatment. The impurities diffuse into the semiconductor substrate. This method has the advantage of being able to form an impurity region with a relatively simple operation without using expensive equipment.

However, when an insulating film, a planarizing film, or a protective film is formed on a semiconductor substrate, a coating liquid for forming a ceria-based coating film is used. The coating liquid for forming a cerium oxide-based coating film, for example, a hydrolyzate containing alkoxy decane or the like, which is coated on a semiconductor substrate and then heated to form a coating containing cerium oxide as a main component Film (for example, refer to Patent Document 2).

[Patent Document 1] Japanese Patent No. 2,359,591 [Patent Document 2] Japanese Patent Laid-Open No. Hei 9-183948

However, since the doped film described in Patent Document 1 does not contain antimony, it is not possible to form a ceria-based coating film while preventing diffusion of impurities, and to prevent other inclusions from being mixed. Moreover, the impurity diffusion method using the doping film described in Patent Document 1 has a disadvantage that it requires expensive equipment and is not suitable for mass production because the solid diffusion method is used. On the other hand, even if the coating liquid for forming a ceria-based coating film described in Patent Document 2 further contains boron oxide, the impurities cannot be sufficiently diffused, and the target resistance value cannot be achieved.

The present invention has been made in view of the above problems, and an object thereof is to provide a film forming composition which is used for coating a film forming composition in a diffusion method, capable of diffusing a relatively high concentration of impurities, and capable of simultaneously forming a cerium oxide system. membrane.

The present inventors have found that by using a film composition containing a polymer ruthenium compound, an oxide of an impurity element, a salt containing the element, and a porogen, the impurity can be diffused to the ruthenium wafer at a high concentration. In the meantime, at the same time, a cerium oxide-based coating film is formed, and the present invention has been completed.

In particular, it is an object of the present invention to provide the following.

(1) A film-forming composition which is a film-forming composition constituting a diffusion film for diffusing an impurity element into a ruthenium wafer, the composition containing (A) a polymer ruthenium compound, (B) An oxide of the above impurity element or a salt containing the element, and (C) a pore former.

Further, the film-forming composition of the present invention is a film-forming composition constituting a diffusion film for diffusing an impurity element into a ruthenium wafer, the composition containing (A) a polymer ruthenium compound, (B) An oxide of the aforementioned impurity element or a salt containing the element, and (C) a pore former.

Further, the film-forming composition of the present invention may contain, as the component (E), a reducing agent for reducing the component (B) instead of the component (C).

The film forming composition of the invention can be used for the coating diffusion method, and can also diffuse a higher concentration of impurity elements into the germanium wafer, and can form a protective layer of germanium dioxide while diffusing the impurities. Laminating. As a result, it is possible to more effectively diffuse the impurity element while suppressing the incorporation of the inclusions while the impurity is diffused.

Hereinafter, embodiments of the present invention will be described in detail.

<Film forming composition>

In the film-forming composition of the present embodiment, the film-forming composition contains (A) a polymer ruthenium compound, (B) an oxide of an impurity element or a salt containing the element, (C) a pore former, and ( D) A solvent capable of dissolving a polymer ruthenium compound.

[(A) Polymer bismuth compound]

The polymer ruthenium compound contained in the film-forming composition of the present embodiment is not particularly limited. For example, a siloxane-based polymer compound having Si-O bond in the main chain and Si in the main chain may be used. a C-bonded ruthenium-based polymer compound, a polydecane polymer compound having a Si-Si chain in the main chain, and a sulfonium-based polymer compound having a Si-N bond in the main chain; the above. Also, any mixture of these compounds can also be used. Further, among these compounds, a naphthene-based polymer compound is particularly preferably used.

(a siloxane polymer compound)

In the film-forming composition of the present embodiment, the oxime-based polymer compound used as the polymer ruthenium compound is preferably one of at least one of the alkoxy decane represented by the following chemical formula (F). Hydrolysis of the starting materials. A condensation polymer is preferred.

[Chemical Formula 1] R ¹ _n -Si(OR ² ) _4-n (F) (wherein R ¹ is a hydrogen atom or a monovalent organic group, R ² is a monovalent organic group, and n is represented by An integer from 1 to 3).

Here, examples of the monovalent organic group include an alkyl group, an aryl group, a propenyl group, a glycidyl group and the like. Among them, an alkyl group and an aryl group are preferred. The alkyl group preferably has 1 to 5 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and a butyl group. Further, the alkyl group may be linear or branched, and hydrogen may be substituted by fluorine. The aryl group is preferably a carbon number of 6 to 20, and examples thereof include a phenyl group and a naphthyl group.

Specific examples of the compound represented by the chemical formula (F) include the following.

(i) When n=1, examples thereof include monomethyltrimethoxydecane, monomethyltriethoxydecane, monomethyltripropoxydecane, monoethyltrimethoxydecane, and monoethyltriethyl. a monoalkyltrialkoxydecane such as oxydecane, monoethyltripropoxydecane, monopropyltrimethoxydecane or monopropyltriethoxydecane, monophenyltrioxane and monophenyl Monophenyltrialkoxydecane or the like such as triethoxysilane.

(ii) When n=2, it may, for example, be dimethyldimethoxydecane, dimethyldiethoxydecane, dimethyldipropoxydecane, diethyldimethoxydecane, or diethyl a dialkyldialkoxydecane such as diethoxy decane, diethyl dipropoxy decane, dipropyl dimethoxy decane or dipropyl ethoxy decane, diphenyl dimethoxy Diphenyl dialkoxy decane, such as decane or diphenyldiethoxy decane.

(iii) When n = 3, there may be mentioned, for example, trimethylmethoxydecane, trimethylethoxysilane, trimethylpropoxydecane, triethylmethoxydecane, and triethylethoxy group. a trialkyl alkoxy decane such as decane, triethylpropoxy decane, tripropyl methoxy decane or tripropyl ethoxy decane, triphenyl methoxy decane, triphenyl ethoxy decane Wait.

Among them, monomethyltrialkoxydecane such as monomethyltrimethoxydecane, monomethyltriethoxydecane or monomethyltripropoxydecane is preferred.

In the film-forming composition of the present embodiment, the mass average molecular weight of the oxime-based polymer compound is preferably 200 or more and 50,000 or less, and more preferably 1,000 or more and 3,000 or less. When it is in the above range, the coating property and the film forming ability can be improved. Further, the ratio of the above-mentioned siloxane-based polymer compound to the total mass of the film-forming composition is from 1 to 60% by mass, and preferably from 10 to 30% by mass.

The condensation of the alkoxydecane represented by the chemical formula (F) is carried out by hydrolyzing the alkoxydecane in an organic solvent to which an acid catalyst is added, and condensing and polymerizing the obtained hydrolyzate. The alkoxy decane to be added to the reaction may be used singly or in combination of plural kinds.

The hydrolysis and condensation polymerization reaction of the alkoxydecane is, for example, an organic solvent containing one or more alkoxydecanes represented by the chemical formula (F), and an aqueous solution containing an acid catalyst is added dropwise to cause a reaction. Carry it out.

The degree of hydrolysis of the alkoxy decane can be adjusted by the amount of water added, and the amount of water added is generally 1.0 to 10.0 times relative to the total number of moles of the alkoxy decane represented by the above formula (F). Moole number, add. By setting the number of moles of the water addition amount to 1.0 times or more of the total number of moles of the alkoxydecane, the degree of hydrolysis can be sufficiently increased, and formation of a film can be easily performed. On the other hand, by setting the number of moles of the water addition amount to 10.0 times or less of the total mole number of the alkoxydecane, it is possible to suppress the purification of the branched polymer by the condensation polymerization, prevent the gelation, and enhance The stability of the film forming composition.

In addition, the acid catalyst to be added during the hydrolysis reaction and the condensation polymerization reaction of the alkoxydecane represented by the chemical formula (F) is not particularly limited, and any of an organic acid and an inorganic acid which are conventionally used can be used. Examples of the organic acid include carboxylic acids such as acetic acid, propionic acid, and butyric acid, and examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. The acid catalyst may be added directly to the organic solvent in which the alkoxydecane is dissolved or dissolved in the water used for the hydrolysis of the alkoxydecane to be added as an acidic aqueous solution.

Since the film-forming composition contains the polymer ruthenium compound in the above manner, ruthenium dioxide can be formed during the thermal diffusion treatment, and the ruthenium dioxide-based film can be formed. This ruthenium dioxide-based film can prevent the inclusion of inclusions other than the impurities of the diffusion target because it functions as a protective film.

[(B) Impure Elements]

Examples of the impurity element added to the film-forming composition of the present embodiment include boron, gallium, and the like of a group 13 element, phosphorus, arsenic, antimony, and the like of a group 15 element, and other elements such as zinc or copper. Then, the above-mentioned impurity element may be added to the film-forming composition in the form of an inorganic salt such as an oxide, a halide, a nitrate or a sulfate, or a salt of an organic acid such as acetic acid. Specific examples thereof include P ₂ O ₅ and NH ₄ H ₂ . a phosphorus compound such as PO ₄ , (RO) ₃ P, (RO) ₂ P(OH), (RO) ₃ PO, (RO) ₂ P ₂ O ₃ (OH) ₃ , (RO)P(OH) ₂ ; Boron compounds such as B ₂ O ₃ , (RO) ₃ B, RB(OH) ₂ , R ₂ B(OH); H ₃ SbO ₄ , (RO) ₃ Sb, SbX ₃ , SbOX, Sb ₄ O ₅ X, etc. Anthracene compound; arsenic compound of H ₃ AsO ₃ , H ₂ AsO ₄ , (RO) ₃ As, (RO) ₅ As, (RO) ₂ As(OH), R ₃ AsO, RAs=AsR; ₂ , zinc compound such as ZnX ₂ , Zn(NO ₂ ) ₂ ; (RO) ₃ Ga, RGa (OH), RGa(OH) ₂ , R ₂ Ga[OC(CH ₃ )=CH-CO-(CH ₃ )] a gallium compound or the like (however, R represents a halogen atom, an alkyl group, an alkenyl group or an aryl group, and X represents a halogen atom).

Among these compounds, boron oxide, phosphorus oxide or the like is preferably used.

Thus, since the film-forming composition contains an oxide of an impurity element or a salt containing the element, the film-forming composition is coated on a germanium wafer, and then subjected to thermal diffusion treatment to diffuse impurities onto the germanium wafer. in.

The mass ratio of (A) the siloxane polymer compound to (B) the oxide of the impurity element or the salt containing the element is preferably in the range of 1:0.01 to 1:1. By setting the amount of the component (A) within the above range, not only the dopant can be diffused at a high concentration, but also a uniform film can be easily formed.

[(C) pore former]

The pore former in the present invention is a material which is decomposed when baking a coating film formed of a film-forming composition, and forms pores in the finally formed ceria-based coating film. Examples of the pore former include polyolefin-based diols and terminal alkylates thereof, monosaccharides and derivatives thereof such as glucose, fructose, and galactose, and disaccharides and derivatives thereof such as sucrose, maltose, and lactose. And polysaccharides and their derivatives. Among these organic compounds, a polyolefin-based diol is preferred, and a polypropylene glycol is more preferred. The mass average molecular weight of the pore former is preferably 300 or more and 10,000 or less, more preferably 500 or more and 5,000 or less. When the mass average molecular weight is set to 300 or more, when the composition is formed by coating or drying the film, decomposition and volatilization of the pore former can be suppressed, and the film can sufficiently act at the time of thermal diffusion treatment. On the other hand, by setting the mass average molecular weight to 10,000 or less, the pore former can be easily decomposed during thermal diffusion treatment and sufficiently functions.

Further, the content of the pore former in the film-forming composition is preferably 2% by mass to 20% by mass based on the total mass of the film-forming composition, and more preferably 3% by mass to 10% by mass.

As described above, by including the pore former, the film coated on the tantalum wafer can be formed into a composition to form a porous ceria-based film. It is considered that since the ruthenium dioxide-based coating film is porous, the moving speed of the impurity element in the cerium oxide-based coating film can be increased, and the diffusion of the impurity element into the ruthenium wafer can be promoted. Moreover, since the cerium oxide-based coating film formed as described above can be made porous, the etching time afterwards can be shortened. Further, since the pore former is contained, the effect of preventing the diffusion of the impurity element from the outside of the film formed by the film formation composition into the germanium wafer can be enhanced.

Moreover, it is preferable that the pore former exhibits a function as a reducing agent for reducing an impurity element. In other words, the film-forming composition of the present embodiment is a film-forming composition for forming a diffusion film for diffusing an impurity element into a germanium wafer, and the composition contains (A) high. A molecular ruthenium compound, (B) an oxide of the above impurity element or a salt containing the element, and (E) a reducing agent capable of reducing the component (B).

Specific examples of the pore-forming agent that functions as a reducing agent, such as polyolefin-based diols such as polyethylene glycol and polypropylene glycol, and terminal alkylates thereof, monosaccharides such as glucose, fructose, and galactose, and Derivatives, disaccharides and derivatives thereof such as sucrose, maltose, lactose, and polysaccharides and derivatives thereof. Among these organic compounds, a polyolefin-based diol is preferred, and a polypropylene glycol is more preferred.

It is preferred that the reducing agent does not remain in the cerium oxide-based coating after the oxide is thermally diffused. Due to the use of such a compound, its adverse effect on semiconductor characteristics can be removed.

The amount of the pore former to be added can be appropriately set depending on the amount of the oxide of the impurity element added to the film formation composition and the content of the polymer ruthenium compound. The content of the reducing agent in the film-forming composition is preferably from 2% by mass to 20% by mass, more preferably from 3% by mass to 10% by mass based on the total mass of the film-forming composition.

As described above, since the reducing agent capable of reducing the impurity element is contained, the oxide of the impurity element or the salt containing the element can be reduced to easily diffuse into the germanium wafer. Thereby, an impurity semiconductor having a desired resistance value can be easily obtained.

[(D) Solvent]

The film-forming composition of the present embodiment is preferably a solvent-containing material for improving the film thickness and the uniformity and coatability of the coating component. In this case, the solvent can be a commonly used organic solvent. Specific examples thereof include monovalent alcohols such as methanol, ethanol, propanol, butanol, 3-methoxy-3-methyl-1-butanol, and 3-methoxy-1-butanol. An alkyl carboxylate such as methyl-3-methoxypropionate or ethyl-3-ethoxypropionate; a polyvalent alcohol such as ethylene glycol, diethylene glycol or propylene glycol; Alcohol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol single Derivatives of polyvalent alcohols such as butyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate; fatty acids such as acetic acid and propionic acid, acetone, A ketone such as methyl ethyl ketone or 2-heptanone. These organic solvents may be used singly or in combination.

The amount of the solvent to be used is not particularly limited, and the solid content is preferably from 1 to 100% by mass, and from the viewpoint of improving coatability, the amount thereof is more preferably such that the solid content is from 3 to 20% by mass.

[Other Additives] (surfactant)

The film-forming composition of the present embodiment may contain a surfactant as needed. By adding a surfactant, coating properties, flatness, and spreadability for a germanium wafer can be improved. These surfactants may be used singly or in combination.

(other ingredients)

In the film-forming composition of the present embodiment, other resins, additives, and the like can be used in combination within a range that does not impair the effects of the present invention. These resins and additives may be added as appropriate depending on the purpose of use of the film-forming composition.

<Coating film formation, thermal diffusion treatment, etching>

The film-forming composition of the present embodiment is applied to a tantalum wafer to form a film, and further subjected to thermal diffusion treatment to form a ruthenium-based film and to diffuse impurities. Further, if the diffusion of the impurities is to be carried out only in the target region, the formation of the protective film, the pattern formation, and the like are performed before the coating film is formed into a composition.

[Coating film formation]

The coating of the film-forming composition can be carried out by any method generally employed by the manufacturer. Specific coating methods include, for example, a spray coating method, a roll coating method, and a spin coating method. The coating amount of the film-forming composition can be appropriately set depending on the solid content concentration.

After the film-forming composition is applied onto the tantalum wafer, it is preferred to heat-treat the film formed on the tantalum wafer to form a composition. In this way, a coating film can be formed on the germanium wafer.

[thermal diffusion treatment]

The thermal diffusion treatment is performed in order to diffuse the coating film formed on the germanium wafer from the imperfect material into the germanium wafer and form the ceria-based coating film. The thermal diffusion treatment is carried out, for example, from 600 ° C to 1200 ° C. The ruthenium dioxide-based film formed during the thermal diffusion treatment is used as a protective film to prevent other inclusions from diffusing into the ruthenium wafer during thermal diffusion treatment. Therefore, the resistance value of the formed impurity semiconductor can maintain a relatively high degree of precision.

[etching]

The cerium oxide-based film after the thermal diffusion treatment is removed by etching. The etching is carried out using hydrofluoric acid, a mixture of hydrofluoric acid and nitric acid, an aqueous solution of sodium hydroxide or potassium hydroxide, or the like. At this time, in order to shape the pattern, the protective film formed on the lower layer of the ceria-based coating film may be simultaneously removed.

[Examples] <Example 1>

In the film formation composition, "OCD T-1 B type" (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used, and boron oxide was added to the whole to have a concentration of 1.5 g/100 ml, and a polypropylene glycol having a mass average molecular weight of 2000 was added. The concentration was made 5% by mass, and it was prepared.

The film-forming composition was spin-coated on a tantalum wafer "6 inch CZ-N<100>" (manufactured by Mitsubishi Materials Corporation). Each of these was heat-treated at 80 ° C, 150 ° C, and 200 ° C for 60 seconds to form a film.

The film-formed germanium wafer was placed in a nitrogen-filled baking furnace, and fired at 1000 ° C for 15 minutes, 30 minutes, and 45 minutes, respectively, to perform thermal diffusion treatment.

The thermal diffusion-treated ruthenium wafer was immersed in 5% hydrofluoric acid at room temperature for 10 minutes, and the film was etched away from the wafer.

<Example 2>

A film formation composition was prepared in the same manner as in Example 1 except that the polypropylene glycol having a mass average molecular weight of 2000 was added in an amount of 10% by mass, and then a coating film was formed, and thermal diffusion treatment and etching were performed.

<Example 3>

A film formation composition was prepared in the same manner as in Example 1 except that the polypropylene glycol having a mass average molecular weight of 2,000 was added in an amount of 3% by mass. Then, a coating film was formed, and thermal diffusion treatment and etching were performed.

<Example 4>

A film formation composition was prepared in the same manner as in Example 1 except that the polypropylene glycol having a mass average molecular weight of 2,000 was added in an amount of 6% by mass, and then a coating film was formed, and thermal diffusion treatment and etching were performed. In addition, the time of the thermal diffusion treatment was only performed for 30 minutes.

<Example 5>

A film formation composition was prepared in the same manner as in Example 1 except that the polypropylene glycol having a mass average molecular weight of 2,000 was added in an amount of 7% by mass, and then a coating film was formed, and thermal diffusion treatment and etching were performed. In addition, the time of the thermal diffusion treatment was only performed for 30 minutes.

<Example 6>

A film formation composition was prepared in the same manner as in Example 1 except that the polypropylene glycol having a mass average molecular weight of 400 was added in an amount of 5% by mass. Then, a coating film was formed, and thermal diffusion treatment and etching were performed. In addition, the time of the thermal diffusion treatment was only performed for 15 minutes.

<Example 7>

In the film formation composition, "OCD T-1" (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used, and P ₂ O _{5 was} added to the whole to have a concentration of 1.5 g/100 ml, and a polypropylene glycol having a mass average molecular weight of 4000 was added. The concentration was made 6% by mass, and it was prepared.

This film was formed into a composition, and a coating film was formed in the same manner as in the Example, followed by thermal diffusion treatment at 900 °C. This thermal diffusion treatment took only 30 minutes.

<Comparative Example 1>

A film formation composition was prepared in the same manner as in Example 1 except that the polypropylene glycol having a mass average molecular weight of 2000 was not added, and then a coating film was formed, and thermal diffusion treatment and etching were performed.

<Comparative Example 2>

A film formation composition was prepared in the same manner as in Example 7 except that the polypropylene glycol having a mass average molecular weight of 4000 was not added, and then a coating film was formed, and thermal diffusion treatment and etching were performed.

<Measurement of resistance value>

The resistance values were measured for the etched silicon wafers in the above examples and comparative examples. The change in resistance value due to the difference in the content of polypropylene glycol and the heat diffusion treatment time is shown in Table 1 below.

From Example 1, Example 2, and Comparative Example 1, it was found that the resistance value of the tantalum wafer of Example 1 was lower than that of Comparative Example 1. That is, it is understood that boron oxide is reduced by the addition of polypropylene glycol and efficiently diffused into the germanium wafer. On the other hand, it is understood that the degree of reduction in the electric resistance value of the second embodiment is smaller than that of the first embodiment.

From the first embodiment, the third embodiment, and the comparative example 1, it is understood that the resistance value of the tantalum wafer of the third embodiment is lower than that of the comparative example 1, and the resistance value of the tantalum wafer of the first embodiment is compared with that of the comparative example 1. The person is even lower.

From Example 1 and Examples 4 to 6, it is understood that as the content of the polypropylene glycol having a mass average molecular weight of 2000 increases, the resistance value decreases. Further, in the case of a content of 5% by mass, it is understood that polypropylene glycol having a mass average molecular weight of 2,000 and 400 can be obtained by using a polypropylene glycol having a mass average molecular weight of 2000 (i.e., using a higher molecular weight). value.

Further, from Example 7 and Comparative Example 2, it was found that when polypropylene glycol was added, the impurity concentration was as high as one-twentieth of the total amount, and the same resistance value was obtained as in the case where no polypropylene glycol was added.

Claims (8)

A film forming composition for forming a film forming composition of a diffusion film for diffusing an impurity element into a germanium wafer, the film forming composition comprising: (A) a polymer germanium compound, B) an oxide of the above impurity element or a salt containing the impurity element, and (C) a pore former, wherein the component (C) is a reducing agent for reducing the component (B). The film-forming composition according to claim 1, further comprising (D) a solvent capable of dissolving the polymer ruthenium compound, and the component (C) is a polymer organic compound soluble in the solvent. The film-forming composition according to claim 1, wherein the component (C) is a polyolefin-based diol. The film-forming composition according to claim 1, wherein the component (C) is a polypropylene glycol. The film-forming composition according to claim 1, wherein the component (C) has a mass average molecular weight of 500 or more. The film-forming composition according to claim 1, wherein the aforementioned impurity element is a group 13 element or a group 15 element. The film-forming composition according to claim 1, wherein the aforementioned impurity element is boron or phosphorus. A film forming composition for forming a film forming composition of a diffusion film for diffusing an impurity element into a germanium wafer, the film forming composition comprising: (A) a polymer germanium compound, B) an oxide of the aforementioned impurity element or a salt containing the impurity element, and (E) a reducing agent capable of reducing the component (B).